EP 0 483 497 B1 describes a coke oven levelling bar which comprises two mutually parallel side members extending in the longitudinal direction of the oven and composed of sheet metal. In the space bounded by the side members at a uniform distance, transverse coal entrainers in the form of sheet metal walls of the height of the side members are arranged.
Shortly before the coal pile cone forming during the filling process and below the filling opening of the coke oven chamber reaches the gas collecting space which is to be maintained free, the levelling bar is inserted through the leveller door opening in the coke oven chamber and is moved back and forth to level out the coal pile cone. So that the free gas collection space above the coal is not blocked to a considerable extent, after the insertion of the levelling bar into the oven chamber during the filling process, the coal entrainers do not extend over the entire width of the intervening space between the two side members the coal entrainers are alternately offset to one another and are arranged on one or the other of the two side members. The side members are thus interconnected by spacer bars.
With this levelling bar it has been found that during the levelling, in spite of the alternating spaces of the levelling bar between the side members and the free ends of the coal entrainers, these alternating spaces can be blocked by the coal to be levelled so that the filling gas no longer can be sucked out unhindered to the collector. As a consequence, the emissions are more or less strongly uncontrolled since the filling gas is no longer freely sucked out via the riser pipe.